Bufflehead Cabin

The chemicals, called hydrofluorocarbons (HFCs), were introduced widely in the 1990s to replace ozone-depleting gases used in air conditioners, refrigerators and insulating foam.

They worked: The earth’s protective shield seems to be recovering.

But researchers say what’s good for ozone is bad for climate change. In the atmosphere, these replacement chemicals act like “super” greenhouse gases, with a heat-trapping power that can be 4,470 times that of carbon dioxide.